•___________THE BABY AT BIRTH___________19
fluid which has filled the bag in which the baby has been
enclosed previous to birth, the infant probably hears many
sounds though he does not know their meaning. He may
show that he has heard the sound by a change in movement
or by a change in respiration. He may respond to certain
sounds and not to others., All these conditions should be
carefully controlled in testing the hearing of the newborn.
Marked individual differences in auditory sensitivity have
been observed during the first few days of life. During this
period some infants seem deaf to sounds which later readily
evoke a reaction. Miss Shinn,10 who observed and wrote the
biography of her baby niece, reported the first sign of hear-
ing on the third day when the baby started violently at the
sound of paper being torn. Under carefully controlled con-
ditions the response appears to be related to the intensity
and duration of the sound and the total bodily state of the
individual as well as to age.
Taste. — When a drop or two of water or a weak solution
of sugar, citric acid, quinine, or salt is placed on a newborn
baby's tongue, he is likely to make some kind of facial
grimaces, especially to salt. These grimaces are accompanied
by circulatory and respiratory changes and activity of other
parts of the body. Very young infants appear to differ from
adults in their reactions to citric acid and quinine. They
do not, like adults, find the bitter taste of quinine unpleas-
ant. * As the baby grows older, he gradually sucks longer on
the sweet substances and a shorter time on the bitter and
acid substances,, even trying to push away the unpleasant
substances; or pull his head away from them.* He does not
appear to distinguish mild flavors. Cod-liver oil, castor oil,
and olive oil seem to be equally acceptable. He takes turnip
juice as eagerly as orange juice.
Thirst and Hunger. — Thirst is present at birth and de-
mands satisfaction more frequently than many mothers
realize. ; A thirsty baby will cry as lustily as a hungry one:)
While we do not know whether the baby feels as adults do
10 Millicent ifr. Shinn, The Biography of c Baby, p. 43. Boston: Houghton
Mifflin Company, 1900.